Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D. (Exhibit 1037)
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`UNITED STATES PATENT AND TRADEMARK OFFICE
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`BEFORE THE PATENT TRIAL AND APPEAL BOARD
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`FUJITSU NETWORK COMMUNICATIONS, INC.
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`Petitioner
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`v.
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`CAPELLA PHOTONICS, INC.
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`Patent Owner
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`
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`Inter Partes Review Case No. IPR2015-00726
`Patent No. RE42,368
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`DECLARATION OF JOSEPH E. FORD, Ph.D.
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`Mail Stop “PATENT BOARD”
`Patent Trial and Appeal Board
`U.S. Patent and Trademark Office
`P.O. Box 1450
`Alexandria, VA 22313-1450
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`FNC 1037
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
`TABLE OF CONTENTS
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`B.
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`INTRODUCTION ........................................................................................... 1
`A.
`Background ........................................................................................... 1
`B.
`Qualifications ........................................................................................ 2
`1.
`Education .................................................................................... 2
`2.
`Career History ............................................................................ 2
`3.
`Publications ................................................................................ 3
`4.
`Other Relevant Qualifications .................................................... 3
`THE ‘368 PATENT ........................................................................................ 3
`II.
`III. LIST OF DOCUMENTS CONSIDERED IN FORMULATING MY
`OPINION ........................................................................................................ 4
`IV. TECHNICAL BACKGROUND ..................................................................... 6
`A. Optical switching for telecommunications ........................................... 6
`1.
`Fiber cross-connects ................................................................... 6
`2. Wavelength switches .................................................................. 8
`Free-space optical systems ................................................................. 10
`1.
`Basic properties of lenses ......................................................... 10
`2.
`Gaussian light beams ................................................................ 12
`3.
`The “Fourier lens” .................................................................... 15
`4.
`Concave mirrors as focusing elements ..................................... 16
`5. Wavelength-dispersive elements .............................................. 17
`STATE OF THE ART AT THE TIME OF THE ALLEGED
`INVENTION ................................................................................................. 21
`A.
`Transparent optical switching prior to the alleged invention ............. 21
`B.
`Reconfigurable Optical Add-Drop Multiplexers ................................ 22
`C. Wavelength Selective Switches .......................................................... 23
`D. MEMS Mirrors ................................................................................... 25
`VI. PERSON OF ORDINARY SKILL IN THE ART ........................................ 28
`VII. OVERVIEW OF THE ‘368 PATENT .......................................................... 28
`A. Operation of the disclosed system of the ’368 Patent ........................ 29
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`V.
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`VIII. THE CLAIMS OF THE ‘368 PATENT ....................................................... 31
`IX. LEGAL STANDARDS ................................................................................. 32
`A. Anticipation ........................................................................................ 32
`B.
`Obviousness ........................................................................................ 33
`CLAIM CONSTRUCTION .......................................................................... 38
`X.
`XI. ANALYSIS OF INVALIDITY .................................................................... 40
`A.
`Summary of Analysis ......................................................................... 40
`B.
`Point 1: Claims 1–6, 9–12 and 15–22 Are Disclosed by Smith ........ 41
`1.
`Operation of the disclosed system of Smith ............................. 41
`2.
`Claim 1 preamble ..................................................................... 47
`3.
`Claim 1 – input port .................................................................. 47
`4.
`Claim 1 – output and other ports .............................................. 47
`5.
`Claim 1 – wavelength selective device .................................... 47
`6.
`Claim 1 – beam-deflecting elements ........................................ 48
`7.
`Claim 2 ..................................................................................... 48
`8.
`Claim 3 ..................................................................................... 49
`9.
`Claim 4 ..................................................................................... 49
`10. Claim 5 ..................................................................................... 50
`11. Claim 6 ..................................................................................... 50
`12. Claim 9 ..................................................................................... 50
`13. Claim 10 ................................................................................... 51
`14. Claim 11 ................................................................................... 51
`15. Claim 12 ................................................................................... 51
`16. Claim 15 ................................................................................... 52
`17. Claim 16 ................................................................................... 52
`18. Claim 17 ................................................................................... 52
`19. Claim 18 ................................................................................... 53
`20. Claim 19 ................................................................................... 53
`21. Claim 20 ................................................................................... 54
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`22. Claim 21 ................................................................................... 54
`23. Claim 22 ................................................................................... 54
`Point 2: Claims 1, 2, 5, 6, 9–12, and 15–21 Are Not Innovative
`in View of Bouevitch and Carr ........................................................... 55
`1.
`Operation of the disclosed system of Bouevitch ...................... 55
`2.
`Carr reference ........................................................................... 59
`3.
`Combination of Bouevitch with Carr ....................................... 60
`Point 3: Claims 1–4, 17 and 22 Are Not Innovative in View of
`Bouevitch and Sparks ......................................................................... 88
`Point 4: Claims 1–6, 9–12 and 15–22 Are Not Innovative in
`View of the Combination of Smith and Tew .................................... 103
`Point 5: Claims 1, 2, 5, 6, 9–12 and 15–21 Are Not Innovative
`in View of the Combination of Bouevitch, Carr and Tew ............... 107
`Point 6: Claims 1–4, 17 and 22 Are Not Innovative in View of
`the Combination of Bouevitch, Sparks and Tew .............................. 108
`XII. CONCLUSION ........................................................................................... 108
`XIII. PROFESSIONAL HISTORY ..................................................................... 109
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`I, Joseph E. Ford, hereby declare as follows:
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`I.
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`INTRODUCTION
`A. Background
`[Intentionally left blank].
`1.
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`2.
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`I have been retained to act as an expert witness on behalf of Fujitsu
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`Network Communications, Inc. (“FNC” or “Petitioner”) in connection with the
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`above captioned Petition for Inter Partes Review of U.S. Patent No. RE42,368
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`(“Petition”). I understand that this proceeding involves U.S. Patent No. RE42,368
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`(“the ‘368 Patent”), titled “Reconfigurable Optical Add-Drop Multiplexers with
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`Servo-Control and Dynamic Spectral Management Capabilities.” The ‘368 Patent
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`is provided as Exhibit 1001.
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`3.
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`I understand that Petitioner challenges the validity of Claims 1-6, 9-12
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`and 15-22 of the ‘368 Patent (the “challenged claims”).
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`4.
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`I have reviewed and am familiar with the ‘368 Patent as well as its
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`prosecution history. The ‘368 prosecution history is provided as Exhibit 1002.
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`Additionally, I have reviewed materials identified in Section III.
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`5.
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`As set forth below, I am familiar with the technology at issue as of
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`both the August 23, 2001 filing date of the application which led to the
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`‘368 Patent, and the March 19, 2001 priority date corresponding to the filing of
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`Provisional Patent Application No. 60/277,217. I have been asked to provide my
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`technical review, analysis, insights, and opinions regarding the prior art references
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`that form the basis for the Petition. In forming my opinions, I have relied on my
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`own experience and knowledge, my review of the ‘368 Patent and its file history,
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`and of the prior art references cited in the Petition.
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`6. My opinions expressed in this Declaration rely to a great extent on my
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`own personal knowledge and recollection. However, to the extent I considered
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`specific documents or data in formulating the opinions expressed in this
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`Declaration, such items are expressly referred to in this Declaration.
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`7.
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`I am being compensated for my time in connection with this IPR at
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`my standard consulting rate, which is $500 per hour.
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`B. Qualifications
`Education
`1.
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`8.
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`Career History
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`2.
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`9.
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`18.
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`Publications
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`3.
`[Intentionally left blank].
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`4. Other Relevant Qualifications
`[Intentionally left blank].
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`[Intentionally left blank].
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`[Intentionally left blank].
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`II. THE ‘368 PATENT
`19. The above-referenced IPR petition seeks review of U.S. Patent No.
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`RE42,368 (“the ‘368 Patent”), Ex. 1001. The ‘368 Patent is a reissue of U.S.
`
`Patent No. 6,879,750. The ‘368 Patent is among a number of patents that
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`ultimately claim priority to U.S. Provisional Application No. 60/277,217, filed on
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`March 19, 2001. The chain is as follows: U.S. Application No. 09/938,426, now
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`U.S. Patent No. 6,625,346, was filed on August 23, 2001. U.S. continuation Patent
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`Application No. 10/005,714, now U.S. Patent No. 6,687,431, was filed on
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`November 7, 2001. U.S. continuation Patent Application No. 10/745,364 was filed
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`on December 22, 2003 and led to the issuance of U.S. Patent No. 6,879,750. I
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`understand that the ‘368 Patent is currently assigned to Capella Photonics, Inc.
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`(“Capella”).
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`20. The technology related to the claims of the ‘368 Patent has
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`applications in fiber optic communications as, for example, switches, filters, and
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`attenuators.
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`21. Tai Chen, Jeffrey P. Wilde and Joseph E. Davis are listed as the
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`inventors for the ‘368 Patent.
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`III. LIST OF DOCUMENTS CONSIDERED IN FORMULATING MY
`OPINION
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`22.
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`In formulating my opinion, I have considered all of the following
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`documents:
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`Description
`Exhibit
`Ex. 1001 U.S. Patent No. RE42,368 to Chen et al.
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`Ex. 1002 U.S. Patent No. 6,498,872 to Bouevitch et al.
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`Ex. 1003 Prosecution History for U.S. Patent No. RE42,368.
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`Ex. 1004 Joseph E. Ford et al., Wavelength Add-Drop Switching Using Tilting
`Micromirrors, 17(5) Journal of Lightwave Technology 904 (1999).
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`Ex. 1005 U.S. Patent No. 6,442,307 to Carr et al.
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`Ex. 1006 U.S. Patent No. 6,625,340 to Sparks et al.
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`Ex. 1007 U.S. Patent Publication No. 2002/0081070 to Tew.
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`Ex. 1008 U.S. Provisional Patent Application No. 60/250,520 to Tew.
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`Ex. 1009 U.S. Patent No. 6,798,941 to Smith et al. (“Smith”)
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`Ex. 1010 U.S. Provisional Patent Application No. 60/234,683 to Smith et
`al. (“Smith Provisional”)
`Ex. 1011 J. Alda, “Laser and Gaussian Beam Propagation and Transformation,”
`in Encyclopedia of Optical Engineering, R. G. Driggers, Ed. Marcel
`Dekker, 2003, pp. 999–1013. (“Alda”)
`Ex. 1012 Joint Claim Construction and Prehearing Statement, Capella
`Litigation, Case No. 3:14-cv-03348-EMC, Dkt. 151.
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`Ex. 1013 Newton’s Telecom Dictionary (17th ed. 2001) (excerpted).
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`Ex. 1014 Fiber Optics Standard Dictionary (3rd ed. 1997) (excerpted).
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`Ex. 1015 Webster’s New World College Dictionary (3rd ed. 1997) (excerpted).
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`Ex. 1018 U.S. Patent No. 6,253,001 to Hoen.
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`Ex. 1019 U.S. Patent No. 6,567,574 to Ma et al.
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`Ex. 1020 U.S. Patent No. 6,256,430 to Jin et al.
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`Ex. 1021 U.S. Patent No. 6,631,222 to Wagener et al.
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`Ex. 1022 U.S. Patent No. 5,414,540 to Patel et al.
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`Ex. 1023 U.S. Patent Publication No. 2002/0097956.
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`Ex. 1024 Shigeru Kawai, Handbook of Optical Interconnects (2005) (excerpted).
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`Ex. 1025 U.S. Patent No. 6,798,992 to Bishop et al.
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`Ex. 1026 Joseph W. Goodman, Introduction to Fourier Optics, Second Edition,
`McGraw-Hill (1996).
`Ex. 1027 U.S. Patent No. 6,204,946 to Aksyuk et al.
`
`Ex. 1028 L.Y. Lin, “Free-Space Micromachined Optical Switches for Optical
`Networking, IEEE Journal of Selected Topics In Quantum
`Electronics,” Vol. 5, No. 1, pp. 4–9, Jan./Feb. 1999.
`
`Ex. 1029 S.-S. Lee, “Surface-Micromachined Free-Space Fiber Optic Switches
`With Integrated Microactuators for Optical Fiber Communications
`Systems,” in Tech. Dig. 1997 International Conference on Solid-State
`Sensors and Actuators, Chicago, June 16-19, 1997, pp. 85–88.
`Ex. 1030 H. Laor, “Construction and performance of a 576×576 single-stage
`OXC,” in Tech. Dig. LEOS ’99 (vol. 2), Nov. 8–11, 1999, pp. 481–482.
`
`Ex. 1031 R. Ryf, “1296-port MEMS Transparent Optical Crossconnect with 2.07
`Petabit/s Switch Capacity,” in Tech. Dig. OSA Conference on Optical
`Fiber Communication, March 2001, pp. PD28-1–PD28-3.
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`Declaration of Joseph E. Ford, Ph.D.
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`Ex. 1032 A. Husain, “MEMS-Based Photonic Switching in Communications
`Networks,” in Tech. Dig. OSA Conference on Optical Fiber
`Communication, 2001, pp. WX1-1–WX1-3.
`Ex. 1033 U.S. Patent No. 5,661,591 to Lin et al.
`
`Ex. 1034 H. Laor et al., “Performance of a 576×576 Optical Cross Connect,”
`Proc. of the Nat’l Fiber Optic Engineers Conference, Sept. 26-30,
`1999.
`Ex. 1035 V. Dhillon. (2012, Sep. 18). Blazes and Grisms. Available:
`http://www.vikdhillon.staff.shef.ac.uk/teaching/phy217/instruments/ph
`y217_inst_blaze.html. (“Dhillon”)
`Ex. 1036 Fianium Ltd. WhiteLase SC480 New Product Data Sheet. Available:
`http://www.fianium.com/pdf/WhiteLase_SC480_BrightLase_v1.pdf.
`(“Fianium”)
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`23.
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`I have reviewed the substance of the Petition for inter partes review
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`submitted with this Declaration (and I agree with the technical analysis that
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`underlies the positions set forth in the Petition).
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`IV. TECHNICAL BACKGROUND
`A. Optical switching for telecommunications
`Fiber cross-connects
`1.
`24. Optical fiber network systems most preferably have a flexible
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`capability of provisioning so that bandwidth may be reconfigured to accommodate
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`changes in demand or to recover from faults.
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`25. At the coarsest level of network provisioning, links originating at
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`various geographic locations and entering a service facility may be selectively
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`interconnected with each other to allocate entire fiber paths to link locations. A
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`traditional way to implement this function is by means of a patch panel, an
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`example of which is pictured below, whereby fibers from various geographic
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`locations may be connected by installing short patch cables manually.
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`If such changes are frequent, however, the cost and delay of “truck rolls” to bring
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`technicians to service facilities may become onerous. Therefore, an automated
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`means for whole-fiber provisioning is desirable.
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`26. The graphic below shows a possible arrangement for what is called a
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`space-division switch, or space switch, using arrays of computer-controlled
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`mirrors, that implements the same function as a patch panel.1
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`1 It is desirable for a switch to be bidirectional, i.e., for signals to be routed reliably
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`from “outputs” to “inputs” as well as from “inputs” to “outputs.” This can
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`generally be achieved with suitable engineering.
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`Inter Partes Review of USPN RE42,368
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`27. Such a switch may be referred to as an optical cross-connect (OXC).
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`In operation, the optical signal from an input fiber is collimated by means of a lens
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`and continues in the form of a pencil-like beam to a dedicated mirror in a first
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`array. The mirror tilt is adjusted to point the reflected beam at the mirror
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`corresponding to the desired output fiber. The second mirror is adjusted to point
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`its reflected beam so that it couples into the output fiber through its collimator.
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`While two separate mirror arrays are shown in the graphic above, the same concept
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`may be implemented with a single mirror array. Because the mirrors are under
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`computer control, no trucks need roll, and network operational costs can be
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`reduced.
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`2. Wavelength switches
`28. The granularity of such provisioning is coarse—a single fiber may
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`carry multiple terabits per second (Tb/s) in each direction—and it is desirable to be
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`able to allocate smaller chunks of bandwidth among fibers.
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` Wavelength-division multiplexing (WDM) is used to impress multiple
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`29.
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`Tb/s of information onto a single fiber. This is done by dividing the spectrum of
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`light into wavelength channels, each of which is capable of carrying distinct
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`information. Because power in different channels does not overlap in wavelength,
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`a single channel or set of channels may be split off—demultiplexed— from a fiber
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`by means of wavelength filtering. Many optical techniques for wavelength
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`selectivity have been employed for wavelength multiplexing and demultiplexing.
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`Gratings capable of dispersing light by wavelength have been used in this regard to
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`create devices that can add (or drop) wavelengths or groups of wavelengths to (or
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`from) a fiber. If individual wavelength channels can be reallocated among fibers,
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`provisioning can be effected with a granularity of tens of Gb/s.
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`30. Prior to the alleged invention, it was known to implement wavelength
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`control in a space switch to effect wavelength provisioning in a remotely
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`controllable fashion. This can be done by using space switches in conjunction with
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`wavelength multiplexers and demultiplexers. In the exemplary system shown in
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`the graphic below, for example, a demux element places each wavelength channel
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`from a WDM input port onto a distinct optical path. Then, space switches are used
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`to send each wavelength to a desired destination port. Multiple wavelengths
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`intended for a destination port are combined by a mux element. Multiplexing and
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`switching functions can be implemented in various ways.
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`Free-space optical systems
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`B.
`31. The art discussed in this Declaration employs optical architectures
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`based at least in part on free-space propagation, i.e., optical propagation that is not
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`confined to a fiber or other kind of waveguide. It is useful to understand the
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`principles by which such systems function.
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`Basic properties of lenses
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`1.
`32. Focusing elements such as lenses and concave mirrors are long-
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`known components of free-space optical systems. They groom light emerging
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`from fibers, and they also operate on image fields bearing many independent
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`channels of light.
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`33. The illustration below highlights certain properties of ideal, thin
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`lenses that are exploited in free-space systems. At left is a ray optics picture of
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`propagating beams. An ideal lens is characterized by its focal distance f.
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`Inter Partes Review of USPN RE42,368
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`Rays originating at a focal point (a distance f from the lens center along its axis)
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`are transformed to horizontal rays on the other side of the lens. But also, rays
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`originating at a common point anywhere in a focal plane all are transformed to
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`parallel rays on the other side of the lens. The rays’ common direction may be
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`found by tracing the ray passing through the lens center, which is not deflected.
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`Note that there are no arrows in the ray diagrams to indicate propagation direction:
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`because of the principle of reciprocity, the ray diagrams may be interpreted either
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`for light traveling generally left-to-right or right-to-left. Thus, rays arriving in a
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`common direction also are transformed to pass through the focal plane at a
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`common point. These basic phenomena underlie the imaging properties of lenses.2
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`2 Single-lens imaging is often depicted as illustrated below, according to the
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`equation 1/S1 + 1/S2 = 1/f:
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`34. The image at right in the illustration above shows qualitatively how
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`beams having lateral extent are transformed by lenses. A collimated beam (one
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`having flat wavefronts) many wavelengths in diameter remains substantially
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`collimated until the lens transforms it into a converging beam that attains its
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`minimum spot size in the focal plane, which size may be of the order of a few
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`wavelengths. Reciprocally, a diverging beam emerging, e.g., from a cleaved,
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`single-mode fiber end in the focal plane, is collimated by the lens. Note that the
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`paths of the extended beams’ central axes are the same as in the simple ray picture
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`of lens behavior.3
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`2. Gaussian light beams
`35. Gaussian beams are solutions of a useful approximation to the
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`electromagnetic wave equation and are important in the field of optical switching.
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`3 The colors in the above diagram are provided for illustration only, and are not
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`meant to convey wavelength information. The focal distance of actual physical
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`lenses may vary non-negligibly with wavelength.
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`A radially symmetric Gaussian beam g with waist radius w0 has a field profile at its
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`waist (narrowest point) of the form
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`𝑔𝑔(𝑥𝑥,𝑦𝑦)=𝑒𝑒−𝑟𝑟2/𝑤𝑤02= 𝑒𝑒−(𝑥𝑥2+𝑦𝑦2)/𝑤𝑤02
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`The waist radius w0 is the radius r at which the field amplitude takes on 1/e (i.e.,
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`about 37%) of its peak value. The plots below show such a radially symmetric
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`Gaussian profile:
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`The plot below shows a snapshot of the oscillatory field (red for positive, blue for
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`negative) in the vicinity of the waist of a radially symmetric Gaussian beam. The
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`plot would look the same along a y–z section. It is apparent that the wavefront is
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`flat only at the waist, and exhibits converging or diverging behavior elsewhere.
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`The divergence angle of the beam as it propagates past its waist depends on the
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`optical wavelength and on the waist radius:
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`So, for a given wavelength, the divergence angle is practically inversely
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`proportional to the waist radius.
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`36. Lenses alter optical beams by imposing spatially varying delays on the
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`wavefronts incident upon them. The graphic below shows a diverging Gaussian
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`beam being substantially collimated by a converging lens:
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`The thick part of the lens at its axis delays light more than the thinner parts away
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`from the axis, and reduces the curvature of the phase fronts of the beam. A beam
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`with greater focusing power would transform the incident diverging beam to a
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`converging beam.
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`Declaration of Joseph E. Ford, Ph.D.
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`37. Radially symmetric Gaussian beams are not the most general type of
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`Gaussian beam. Gaussian beams can have elliptical cross section, and beam waists
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`in orthogonal directions may occur at different positions along the propagation
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`direction. A general treatment of Gaussian beams is found in Alda. Ex. 1011.
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`The “Fourier lens”
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`3.
`38. The designation “Fourier lens” or “Fourier transform lens” is
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`commonly used in the art to refer to lenses that convey multiple information beams
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`within a system and are used to perform certain tasks. This designation arises from
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`a connection between lens phenomenology and the theory of Fourier signal
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`analysis.4
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`39. A useful consequence of this connection is routinely expressed as the
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`rule that lenses “transform angles to displacements and displacements to angles.”
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`This behavior can be observed in the above ray-optics illustration of light
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`propagating between the focal planes of a lens. The graphic below depicts the
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`“angles to displacements” principle more generally, in three dimensions:
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`4 This correspondence is elucidated in Ex. 1026.
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`Inter Partes Review of USPN RE42,368
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`y
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`x
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`y
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`x
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`z
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`Beams (depicted as rays for clarity) can be incident on the lens at any angle to its
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`axis (the z-axis in the graphic) and in any direction in the x–y plane.5 In the focal
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`plane behind the lens, a beam is seen to be displaced in the x–y plane in the same
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`direction as its angular tilt before traversing the lens, and by an amount
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`corresponding to the magnitude of the tilt. Consequently, a beam can be directed
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`to pierce the rear focal plane of the lens at any point, by controlling its angular
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`attitude in two directions.
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`Concave mirrors as focusing elements
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`4.
`40. Concave mirrors as well as positive lenses may be employed as
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`5 Rays lying strictly in the x–z or y–z planes are shown for the sake of clarity.
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`Declaration of Joseph E. Ford, Ph.D.
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`focusing elements (and Fourier transforming elements) in free-space optical
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`systems. The illustration below shows both a converging lens and a focusing
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`mirror having a common focal length f. Similarly to the lens, the mirror causes
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`parallel incident rays to converge to a common point on a focal plane; the fact that
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`incident and reflected light beams propagate on the same side of the mirror can be
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`an advantage in system design.
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`5. Wavelength-dispersive elements
`41. As noted above, it was known to employ dispersive elements such as
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`gratings in free-space systems to separate individual wavelength channels from a
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`WDM signal, so that they could be treated independently. The graphic below
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`shows both a prism and a grating that perform this function:
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`Inter Partes Review of USPN RE42,368
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`The prism deflects light because the thin end imposes a smaller delay on a light
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`wave passing through it than the thick end. But also, in terms of oscillation periods
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`of the optical field, a given time delay represents more cycles of short-wavelength
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`(e.g., blue) light than of long-wavelength (red) light. A prism deflects shorter
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`wavelengths more than longer wavelengths.
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`42. A grating disperses light by diffraction. The illustration below depicts
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`an amplitude grating in cross-section because it modulates transmitted wave
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`amplitude in a spatially periodic fashion. The grating can be thought of as an
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`opaque sheet with narrow, parallel slits cut into it at equal intervals. The wave
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`emerging from each narrow slit diverges substantially. Zero-phase contours of the
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`incident and diffracted waves are shown as blue lines. Thus, there is more than
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`one direction in which the “wavelets” will interfere constructively to form a
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`diffracted wave, each referred to as an “order”.6 The angle θ through which
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`normally incident light is diffracted into the first order (the least angle of
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`deflection)7 is approximately the ratio of the optical wavelength λ to the grating
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`pitch Λ (θ ≈ λ/Λ), so that a finer-pitch grating will deflect a given beam through a
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`larger angle.
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`43. The relative strength of the various diffracted orders depends on the
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`nature of the grating. Amplitude gratings incur an efficiency penalty because some
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`incident light power is inherently blocked. Phase gratings do not systematically
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`6 This construction is due to Huygens and was developed further by Young and
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`Fresnel in the early 19th Century. See, e.g., Ex. 1026 at 33–35.
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`7 The wavefront corresponding to the first diffracted order is the envelope formed
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`when adjacent wavelets are considered that have a relative phase difference of 2π,
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`i.e., of a single, full wave. If adjacent wavelets are considered that have a relative
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`delay of two waves, their constructive interference forms the second diffracted
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`order.
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`absorb light, but function by imposing a periodically varying time delay on
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`incident light by (in the case of surface relief gratings) modulating the depth of
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`periodic surface features. The graphics below highlight certain aspects of planar,
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`reflective, surface-relief gratings:
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`(Ex. 1035)
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` (Ex. 1035) (Ex. 1036)
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`Declaration of Joseph E. Ford, Ph.D.
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`44. The image at lower left shows a few periods of a blazed grating, with
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`a groove profile designed to maximize the power directed to a desired diffracted
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`order. In the sketch at top, the “zeroth order” is undiffracted light, which reflects
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`from the plane of the grating as from a flat mirror, and so makes the same angle
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`with the grating perpendicular as the incident radiation. The direction of first-order
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`diffracted light is determined by the grating pitch d and the wavelength (and
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`direction) of incident light. Due to the choice of blaze angle, the incident radiation
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`and the first diffracted order make the same angle with the facet normal.
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`Consequently, most of the incident light will be diffracted into the first order. The
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`image at lower right shows diffraction of a beam of white light from a blazed
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`grating. Two diffracted orders are apparent, with the first order considerably
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`brighter. The second order disperses the wavelength spectrum over twice the angle
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`as the first. Groove profile may be designed to maximize diffraction efficiency
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`into a particular order, which flexibility is useful in the design of wavelength-
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`selective systems.
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`V.
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`STATE OF THE ART AT THE TIME OF THE ALLEGED
`INVENTION
`A. Transparent optical switching prior to the alleged invention
`45. The advantages offered by transparent optical switching have been
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`appreciated for several decades. Before transparent switching, network
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`provisioning had to be implemented either with fiber patch panels, or by
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`Inter Partes Review of USPN RE42,368
`Declaration of Joseph E. Ford, Ph.D.
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`converting individual wavelength signals to the electrical domain, using electrical-
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`domain switching technologies, and then re-c